1. Field of the Invention
The present invention relates to a method for forming a molded portion of a weather strip, and more particularly to a method for forming a molded portion composed of solid rubber onto an end of an extruded weather strip having a solid rubber portion and a sponge rubber portion.
2. Description Related Art
Examples of the weather strip provided with the above-described type of the molded portion include a roof side weather strip to be attached along a roof side of a motor vehicle, and a door weather strip to be attached to a door frame of a motor vehicle.
In the motor vehicle as shown in FIG. 7, a roof side weather strip 1 is attached to a roof side 4 of a vehicle body for providing a seal between the roof side 4 and a door frame 5. A door glass weather strip 2 is attached to the door frame 5 for providing a seal between the door frame 5 and a peripheral edge of a door glass 6, as shown in FIG. 8.
The roof side weather strip 1 has a base portion 11 composed of solid rubber, and sealing portions 12, 13 composed of sponge rubber. The door glass weather strip 2 has a base portion 21 composed of solid rubber, a sealing portion 22 composed of sponge rubber, and a tubular portion 24 composed of solid rubber provided with a sealing portion 23 composed of sponge rubber. These weather strips 1, 2 are generally formed by extrusion.
A corner portion of the roof side weather strip 1, which is designated by reference character A in FIG. 7 has a molded portion 1C by which ends of two extruded weather strips 1A, 1B are connected, as shown in FIG. 9 (U.S. Pat. No. 4,884,370).
Molded portion 1C has been conventionally formed by inserting the ends of the two extruded weather strips 1A, 1B in a cavity of a mold so as to face one another, and injecting a molding material composed of solid rubber softer than that for the base portion 11 of the extruded weather strips 1A, 1B into the cavity under a predetermined injection pressure.
However, this conventional method has the following problem. When the cavity of the mold is filled with the molding material, the material forcefully pushes the ends of the extruded weather strips 1A, 1B. At this time, the sealing portions 12, 13, which are composed of a sponge rubber, can be deformed easily by the molding material, and as a result, undulations 8 are generated in the end portions of the sealing portions 12, 13, as shown in FIG. 9. These undulations 8 decrease the sealing ability of the sealing portions 12, 13 and detract from their outward appearance.
The generation of these undulations 8 can be prevented by decreasing the injection pressure of the molding material. However, as the injection pressure decreases, the molding material tends not to completely fill the cavity of the mold.